Molecular models for nucleic acids

ABSTRACT

Molecular models for use in constructing, and experimenting with, the different secondary and tertiary structures of polynucleotides, using specially designed plastic blocks representing mononucleotides, are described. These models are composed of blocks that can be both assembled in vertical stacks to illustrate single-stranded, random coil, polynucleotides and joined in horizontal pairs to illustrate hydrogen-bonded nucleotide pairs. A combination of both these manners of assembly would illustrate double-stranded right-handed, helical polynucleotides whose strands were of opposite polarity.

United States Patent [191 Dingman, II

451 Dec. 17, 1974 MOLECULAR MODELS FOR NUCLEIC ACIDS Inventor: Charles Wesley Dingman, II, 10113 Bevern Ln., Potomac, Md, 20854 Filed: Nov. 26, 1973 Appl. No.: 419,082

US. Cl. 35/18 A, 46/25 Int. Cl G09b 23/20, A63h 33/08 Field of Search 35/18 A; 46/25, 26

References Cited UNITED STATES PATENTS 9/1961 Marini 46/26 7/1965 Lepper 46/25 l/1967 Klotz 35/18 A X 7/1971 Baker 35/18 A 3,804,417 4/1974 Dawson 35/18 A X Primary Examiner--Harland S. Skogquist 5 7 ABSTRACT Molecular models for use in constructing, and experimenting with, the different secondary and tertiary structures of polynucleotides, using specially designed plastic blocks representing mononucleotides, are described. These models are composed of blocks that can be both assembled in vertical stacks to illustrate single-stranded, random coil, polynucleotides and joined in horizontal pairs to illustrate hydrogenbonded nucleotide pairs. A combination of both these manners of assembly would illustrate double-stranded right-handed, helical polynucleotides whose strands were of opposite polarity.

1 Claim, 12 Drawing Figures PATENTE SEC] 7 I974 SHEET '3 OF 3 HEM MOLECULAR MODELS FOR NUCLEIC ACIDS SUMMARY Herein are described new molecular models of mononucleotides. The purpose of such structures is to enable researchers and educators in the field of the structure and function of nucleic acids to rapidly and inexpensively constuct, without tools, small scale models of long chain, single and double stranded, polynucleotides of defined sequence and configuration. It is intended that these assembled scale models be sufficiently strong to enable the user to explore the various possible configurations of a polynucleotide chain without the individual units coming apart. Previously designed and manufactured models either lacked the necessary strength, rigidity and space-filling properties of the herein described models, or were inordinately large, expensive and difficult to assemble, especially if models of long chain polynucleotides were desired.

In the models described herein the individual units, or blocks, representing mononucleotides, are to made in two configurations (labeled herein A and B).

FIG. 1 shows a plan of a block of configuration A.

FIG. 2 shows a front elevation of a block of configuration A.

FIG. 3 shows a plan of a block of configuration B.

FIG. 4 shows a front elevation of a block of configuration B.

FIG. 5 shows a front elevation of the metal or plastic spring clip used to hold a block of configuration A to a block of configuration B (e.g.' right side of configuration A shown in FIG. 1 to left side of configuration B shown in FIG. 3).

FIG. 6 shows a plan of the spring clip shown in FIG. 5.

FIG. 7 showsa perspective view of the spring clip shown in FIGS. 5 and 6.

FIG. 8 shows a perspective view of two blocks, one of configuration A and one of configuration B juxtaposed as they would be in use, illustrating a hydrogenbonded nucleotide pair (the spring clip holding these two blocks in this position is not shown in place).

FIG. 9 shows a different perspective view of an identical pair of blocks (also without the spring clip in place) to that shown in FIG. 8. The pair of blocks shown in FIG. 9 is rotated 36 with respect to the pair shown in FIG. 8 so as to show how the pair of blocks shown in FIG. 8 would be fitted to the pair of blocks shown in FIG. 9 to construct vertical stacks illustrating I right-handed, double-helical polynucleotides.

FIG. 10. shows a plan of the connecting pin used to tightly secure (when desirable) pairs of blocks of identical configuration in vertical arrays.

FIG. 11 shows a side elevation view of two blocks of identical configuration (configuration B) seated properly in a vertical stack with the connecting pin (FIG. 10) properly positioned in the receptacles provided for it in each block. (A mirror image of FIG. 11 would pertain for two blocks of configuration A.)

FIG. 12 is an identical view of the same two blocks shown in FIG. 11 and shows how vertically adjoining blocks can be rotated about their connecting pin to provide gaps between adjacent blocks. These gaps enable the user to insert structures (representing, for example, drugs which intercalate between nucleotide pairs of double-stranded polynucleotides) between blocks in vertical arrays, and to remove the spring clip connecting selected pairs of blocks contained within long vertical, double-stranded, arrays to represent localized melting (loss of hydrogen-bonding between nucleotide pairs) of the linkage between blocks of opposite configuration.

DESCRIPTION These models shall consist of blocks having two basic configurations (Configuration A, shown in FIGS. 1 and 2, and configuration B, shown in FIGS. 3 and 4); a spring clip (shown in FIGS. 5, 6 and 7) to hold blocks of configuration A together with blocks of configuration'B in horizontal pairs, and a flexible connecting pin (shown in FIGS. 10, l1 and 12) to hold blocks of identical configuration in vertical arrays.

Blocks having configuration A shall be made of strong, slightly flexible and resilient plastic in the following four color patterns:

a. Red with a white outside face (the curved face having the two receptacles for the connecting pins) and the letter A (representing ade osine 5'- monophosphate) in black on the outside face.

b. Green with a white outside face having the letter G (representing guanosine 5'-monophosphate) in black on the same outside face as described in (a).

c. Blue with a white outside face having the letter T (representing thymidine 5 '-monophosphate or uridine 5'-monophosphate) in black on the same outside face as described in (a).

d. Yellow with a white outside face having the letter C (representing cytidine 5'-monophosphate) in black on the same outside face as described in (a).

Blocks having configuration B shall be made of the same material as blocks of configuration A and in the same four color patterns as described above for configuration A except the outside faces in each case shall be black and the corresponding letter in each case shall be white.

The spring clip which holds two blocks of different configurations together in horizontal pairs shall be constructed of spring steel (rust proof) or tough, flexible plastic.

The connecting pin which holds two blocks of identical configuration together in vertical stacks shall have a circular cross-section, and be constructed of tough, flexible polyethylene.

Each block is to have a thickness of either 3.5 mm (for models of scale 1mm I A.) or 17.5 mm (for models of scale 5mm l A.) and the appropriate outside dimensions (see scale accompanying each sheet of drawings) to represent the approximate space occupied by 5'-mononucleotides with the puckering of their ribose in the C(2)-endo configuration at the scales mentioned above (see FIGS. 1 through 4).

Blocks of both A and B configuration are to have one cavity each facing their inside surface which is positioned so as to receive and firmly hold one end of the spring clip (see FIGS. 1 through 4, 8 and 9).

Blocks of both A and B configuration are to have two cavities each in their outside face which are shaped and positioned so as to receive the male portions of the connecting pin shown in FIG. 10 (see FIGS. 1, 3, 8, 11 and 12). Blocks of both A and B configuration are to have two disc-shaped permanent magnets each, embedded in positions representing the 3' OH of the sugar moiety and the 5'- phosphate moiety, respectively.

The magnetic disc representing the 3' OH group is to be recessed slightly with its south pole exposed (so as to be able to attract and seat the projecting north pole of the magnet representing the 5- phosphate of a neighboring block of similar configuration in vertical arrays). The magnetic disc representing the 5- phosphate group is to project slightly with its north pole exposed (so as to be able to attract and seat with the recessed south pole of the magnet representing the 3' OH group of a neighboring block of similar configuration in vertical arrays (see FIGS. 1 through 4, 8, 9, l1 and 12).

Having described the invention, what is claimed as new and what is desired to be secured by a Patent is:

1. Molecular models of mononucleotides for use in teaching and research consisting of blocks having two configurations of such a design that (a) pairs consisting of one block of each of the two configurations may be 4 held together'firmly in horizontal pairs by easily applied clips tovillustrate hydrogen-bonded nucleotide pairs having opposite polarity at a scale of either 1mm to l A. or 5mm to l A.; (b) many blocks of the same configuration may be snapped easily together by means of pairs of magnetic discs embedded in the blocks and then coupled more strongly, if desired, by means of connecting pins to illustrate semi-flexible, singlestranded polynucleotides to the same scales as referred to in part (a); and (0) many pairs of blocks (consisting of one block of each configuration) may be snapped easily together in vertical arrays (as described in (b) above but with each pair rotated 36 in a right-handed direction with respect to the preceding pair) to illustrate helical doublestranded polynucleotides consisting of two polynucleotide chains of opposite polarity, hydrogen-bonded together, to the same scles as re- 

1. Molecular models of mononucleotides for use in teaching and research consisting of blocks having two configurations of such a design that (a) pairs consisting of one block of each of the two configurations may be held together firmly in horizontal pairs by easily applied clips to illustrate hydrogen-bonded nucleotide pairs having opposite polarity at a scale of either 1mm to 1 A. or 5mm to 1 A.; (b) many blocks of the same configuration may be snapped easily together by means of pairs of magnetic discs embedded in the blocks and then coupled more strongly, if desired, by means of connecting pins to illustrate semi-flexible, single-stranded polynucleotides to the same scales as referred to in part (a); and (c) many pairs of blocks (consisting of one block of each configuration) may be snapped easily together in vertical arrays (as described in (b) above but with each pair rotated 36* in a right-handed direction with respect to the preceding pair) to illustrate helical double- stranded polynucleotides consisting of two polynucleotide chains of opposite polarity, hydrogen-bonded together, to the same scles as referred to in part (a). 